A GIS-Based System to Assess the Environmental Consequence of a Liquid Pipeline Rupture at Watercourse Crossings

Abstract

BGC Engineering Inc. (BGC) was retained by a large pipeline operator to develop a GIS-based system to assess and rank the environmental consequence of a pipeline rupture on watercourse crossings within their pipeline system. Several physical, biological and socio-economic factors contribute to the environmental consequence of a pipeline rupture on a watercourse. This study examined select spatial and vulnerability factors, and did not consider biologic or economic impacts. Three factors were selected as part of the initial study to prioritize the pipeline watercourse crossings according to: (1) size of the watercourse at the pipeline crossing, (2) proximity of each individual crossing to larger downstream watercourses, and (3) pipeline liquid flow rate volume. A spatial analysis was conducted to determine the first two factors, while input for the third factor was provided by the pipeline operator. Watercourse size was determined using Strahler’s stream order classification (Strahler 1952), while proximity to larger downstream watercourses was assessed using a Geographic Information System (GIS). This paper presents an overview of the data sources and methods used to develop an initial screening tool for identifying high consequence crossings within a pipeline system, and highlights the challenges encountered with acquiring and processing data to include in a consequence rating system. As with other pipeline risk assessments, the main challenges of this work include data availability, data integrity and resource limitations. This system is intended to fit within the pipeline operator’s current geohazard integrity management program and direct resources for a multi-year baseline field inspection program.